Arecibo Observatory Decommissioned After Second Cable Breaks
The Arecibo Observatory was already damaged when a main cable snapped. Find out why this closed the facility for good and what the plan is now.
In an earlier story in these pages back in August, we told you about the storm damage that had temporarily shut down the iconic Arecibo Observatory in Puerto Rico. At that time, Francisco Cordova, the observatory’s director, explained, “Our focus is assuring the safety of our staff, protecting the facilities and equipment, and restoring the facility to full operations as soon as possible.”
We now know that the focus on safety has forced a change of plans. The structural damage is so severe that there’s no safe way to repair the observatory.
Instead, the National Science Foundation (NSF), the observatory’s owners, have decided to decommission it. “This decision is not an easy one to make, but safety is the number-one priority,” said Sean Jones, head of the NSF’s mathematical and physical sciences directorate.
Central Role in Astronomy Since 1963
The Arecibo Observatory has played a central role in radio astronomy ever since it opened in 1963. It was the largest radio telescope on Earth for more than half a century until it was finally surpassed by the massive China Sky Eye just last year.
Arecibo’s gigantic dish antenna is 305 metres in diameter. It collects and focuses radio signals received from objects in space.
Radio telescopes have a wide range of uses. Arecibo has investigated phenomena ranging from near-Earth asteroids to Fast Radio Bursts. The NSF paused those activities when one of the auxiliary cables snapped after a storm on August 10. The lines support the 900-tonne instrument platform suspended 140 metres above the dish.
Initial Plan Was to Replace the Cable and Repair the Gash
As the broken cable flailed around, it tore a 30-metre gash in the reflective dish. The initial plan was to replace the cable and repair the rip.
The NSF had to abandon those plans on November 6, when a three-inch main cable attached to the same tower also broke. This was a surprise to everyone involved.
The second and more vital cable gave way at only 60% of its rated strength, and the weather at the time was calm. This suggested that there was a high risk of other cables breaking unexpectedly despite their safety ratings.
Engineering Studies Recommended Shutting Down Facility
The NSF commissioned three independent engineering studies, two of which recommended shutting down the facility. They then hired another firm to adjudicate among the three reports. They agreed with the consensus that the only safe thing to do was to demolish the Arecibo Observatory.
“Until these assessments came in, our question was not if the observatory should be repaired but how. But in the end, a preponderance of data showed that we simply could not do this safely. And that is a line we cannot cross.” said Ralph Gaume, director of the NSF’s astronomy division, at a media briefing the NSF held on November 19.
“Even attempts at stabilization or at testing the cables could result in accelerating the catastrophic failure,” Gaume continued. NSF Director Sethuraman Panchanathan added, “NSF prioritizes the safety of workers, Arecibo Observatory’s staff and visitors, which makes this decision necessary, although unfortunate.”
“Scientists Are Mourning Its Loss”
This has been a blow to the scientific community. The respected science journal Nature called the Arecibo Observatory “one of the most iconic and scientifically productive telescopes in the history of astronomy.” They reported that “scientists are mourning its loss.”
Abel Méndez is an astrobiologist at the University of Puerto Rico. He told Nature, “I am totally devastated.” two radio-astronomy organizations, the National Radio Astronomy Observatory in Charlottesville, Virginia, and the Green Bank Observatory in West Virginia issued a joint statement declaring that, “The Arecibo Telescope is irreplaceable.”
The decommissioning process itself will be a challenging project. The NSF will be putting together what it calls a “technical execution plan.” The foundation will have to ensure compliance with various legal, environmental, safety and cultural needs.
Plan to Preserve Other Facilities at the Observatory
Once the plan is complete and equipment and supplies have been moved outside the danger zone, the NSF will execute a controlled disassembly of the Arecibo Observatory structure. The goal is to preserve other facilities at the observatory wherever possible.
For example, a primary goal is to preserve the light-radar (LIDAR) facility, which is essential to geospace research. The foundation also plans to maintain the visitor center.
They’ll also be keeping a related off-site facility in Culebra, Puerto Rico, that studies cloud cover and precipitation. NSF will also be looking into ways to provide more education at the learning center. Some of the archiving and cataloging functions will continue as well.
“Continue and Build on Arecibo’s Contributions to Science”
The University of Central Florida (UCF) oversees the Arecibo Observatory. UCF President Alexander N. Cartwright said. “UCF stands ready to utilize its experience with the observatory to join other stakeholders in pursuing the kind of commitment and funding needed to continue and build on Arecibo’s contributions to science.”
Director Panchanathan concluded by saying, “For nearly six decades, the Arecibo Observatory has served as a beacon for breakthrough science and what a partnership with a community can look like. While this is a profound change, we will be looking for ways to assist the scientific community and maintain that strong relationship with the people of Puerto Rico.”
We always have more to learn if we dare to know.
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Originally published at http://daretoknow.ca on November 24, 2020.